Study Finds Most People Have High Genetic Risk for Diabetes, Heart Disease and Schizophrenia

A study published in Genome Medicine found that most people have high genetic risk scores for nearly three common diseases, highlighting the importance of interpreting genetic results carefully.

Most People Have High Genetic Risk for Three Common Diseases, Study Finds

A new study has found that most people may have a high genetic risk score for nearly three common diseases, including diabetes, cardiovascular disease and schizophrenia. However, a high genetic risk does not mean that a person will necessarily develop any of these conditions.

Researchers led by the University of Exeter in the United Kingdom examined genetic data to understand the variations commonly found in human DNA and how these variations influence disease-risk assessments. The findings, published in the journal Genome Medicine, provide insights into how genetic testing results should be interpreted in clinical settings.

Study Examines Genetic Risk Across 28 Common Diseases

The research team analysed data from two large population-based resources: the UK Biobank and the United States’ All of Us research programme. Together, these datasets provided whole-genome sequencing information covering nearly one million individuals.

The researchers examined polygenic risk scores for 28 common diseases. These scores combine information from multiple genetic variants to estimate a person’s inherited susceptibility to a particular condition.

According to the study, the average person falls within the highest 10% of genetic risk scores for nearly three conditions. Additionally, approximately one in five people ranks within the top 1% for at least one polygenic risk score.

These findings indicate that elevated genetic risk scores are relatively common. However, they should not be interpreted as evidence that individuals will inevitably develop the diseases associated with those scores.

What Does the Average Human Genome Reveal?

The researchers described the characteristics of an average human genome to help clinicians better understand the genetic variations found in individuals.

According to the study, a typical human genome contains approximately five million genetic variants. These are locations in DNA where an individual's genetic sequence differs from a reference sequence or varies between people.

Around 10,000 of these variants alter gene sequences. Such changes can have different effects, influencing characteristics and biological processes, including lactose intolerance and responses to medicines. Many genetic variations, however, have little or no meaningful effect on health.

The findings reinforce the idea that genetic variation is a normal feature of human biology rather than an unusual occurrence.

Rare Genetic Variants Can Have Different Effects

The analysis also found that each person carries approximately one to three rare genetic variants that have previously been associated with serious genetic diseases.

In addition, individuals typically carry around 50 rare variants whose clinical significance remains uncertain.

The presence of such variants does not automatically indicate that a person has a genetic disorder. Some variants may contribute to disease, while others may have limited effects or require further research before their significance can be established.

The researchers stressed that genetic findings must be assessed in the context of an individual's health, symptoms and other relevant information.

Why a High Genetic Risk Score Does Not Guarantee Disease

Polygenic risk scores estimate susceptibility by combining the effects of numerous genetic factors. They can help identify individuals whose inherited genetic profiles are associated with a higher or lower likelihood of developing certain conditions.

However, these scores do not provide a definitive prediction of an individual's future health.

A person's actual risk can also depend on family history, lifestyle, environmental exposures, existing medical conditions and other biological factors. For example, someone with a high genetic risk score may never develop the associated disease, while another person with a lower score could still develop it.

The researchers therefore emphasised that genetic test results should not be interpreted in isolation or treated as a diagnosis.

Researchers Highlight the Importance of Clinical Context

Senior author Caroline Wright of the University of Exeter said that whole-genome sequencing has become increasingly important for diagnosing genetic diseases, while genetic screening is also being explored as a way to estimate future disease risks.

Wright highlighted that many people may not realise how much genetic variation exists in the human genome. The study aims to establish a clearer picture of what is typically found in an individual's genetic profile.

She also emphasised the need to consider symptoms, family history, clinical findings and environmental influences when interpreting genetic testing results.

According to the researchers, this context is important for healthcare professionals who assess genetic reports and design genetic screening programmes. A better understanding of normal genetic variation may help prevent unnecessary concern arising from results that are not clinically significant.

Study Acknowledges Limitations in Population Diversity

Despite the large datasets used, the researchers acknowledged an important limitation: participation in the underlying studies was skewed towards individuals of Western European ancestry.

This imbalance may limit how accurately some findings apply to people from other ancestral backgrounds. Genetic risk scores developed using one population may not perform equally well in another because the frequency and effects of genetic variants can differ between populations.

The researchers highlighted the need for more diverse genetic datasets to improve the reliability, inclusiveness and clinical usefulness of future genetic research.

Conclusion

The study published in Genome Medicine shows that elevated genetic risk scores are common and that genetic variation is a normal part of human biology. However, genetic susceptibility alone cannot determine whether someone will develop a disease. By combining genetic information with clinical history, lifestyle factors and more representative population data, researchers and healthcare professionals can work towards more accurate and responsible interpretations of genetic testing results.